You get used to the ones you have, but sometimes they're extreme. We have one at home that actually makes people gasp in horror when they catch themselves in it 
But on holiday, it was like a funhouse!
One bedroom had a huge wall mounted 'thin' mirror that stretched my head into the shape of Bert from Sesame Street (Hi Burt!), and a whopper of a wide mirror in the other bedroom. This wasn't so much wide as almost wavy, just like the ones you might see in a funhouse.
The wide mirror stretched my cheeks outwards so that I looked 20 yrs younger, yet unfathomably squat.
Mirror in the bathroom gave us cone shaped foreheads.
Do you have what you would call a true mirror? And if so, how do you know?
Shop windows are notoriously distorted, and the worst changing rooms I can recall were good old marks&spencer's.